Wire-guides are elongate flexible members used to provide a path along which another medical device can be moved. The path provided by the wire-guide can be used to navigate another medical device, such as a catheter, through a body vessel. The use of wire-guides to define such a path is known in the art. Briefly, a wire-guide is navigated through a body vessel toward a point of treatment. Once positioned within the vessel, a second medical device, frequently a cannula such as a catheter is placed over the wire-guide and moved along its length toward the point of treatment. Thus, the wire-guide provides an established path for placing other devices, eliminating the need for performing delicate navigation procedures for each device passed into the vessel.
During placement of a wire-guide, an operator must navigate the wire-guide through the vessel(s). Often, the vessel defines a torturous path due to the presence of natural bends and/or curves, or unnatural impediments, such as tumors, build-ups, and/or strictures. The presence of a torturous path may make navigation of a wire-guide difficult. For example, the presence of an impediment may block the wire-guide from navigating further into the vessel.
The prior art contains many examples of wire-guides having straight flexible tips intended to aid in the navigation around such impediment. The presence of a straight flexible tip, however, may in fact make navigation more difficult. For example, upon encountering an impediment, the straight flexible tip may bend toward one of the vessel walls. Further, the straight tip may bend and turn back upon itself upon encountering the impediment. This formation of an unstable turn in the wire-guide makes further navigation difficult.
One successful device developed to address this need in the art is the loop tip wire-guide disclosed in pending U.S. application Ser. No. 10/719,764, entitled “Loop Tip Wire-guide,” filed Nov. 21, 2003, which claims priority to U.S. Provisional Application Ser. No. 60/430,466, filed Dec. 2, 2002, each of which are incorporated by reference. In this device, a resilient loop positions, and a closure member affixes, the distal end of a wire-guide relative to the wire-guide. When this device is navigated through a body vessel and encounters an impediment, the distal end of the wire-guide does not move relative to the remainder of the wire-guide due to the presence of the loop and closure member. Instead, the loop deforms in response to the impediment. The resiliency of the loop creates a force opposing the impediment and directs the loop away from the impediment. This defines a path for the remainder of the wire-guide to follow and enables the wire-guide to navigate about the impediment and continue along the interior of the vessel.
Yet, additional improved embodiments of a loop tip wire-guide are desirable. For example, the point of treatment may be located in a side branch or beyond a bifurcation of the main vessel. It would be desirable if a loop tip wire-guide provided the user with the greater ability to direct the loop tip of the wire-guide through a main body vessel and into a branch vessel or a bifurcation. For this reason, a steerable wire-guide would be desirable.